Rm. Hansen et Ab. Fulton, DARK-ADAPTED THRESHOLDS AT 10-DEG AND 30-DEG ECCENTRICITIES IN 10-WEEK-OLD INFANTS, Visual neuroscience, 12(3), 1995, pp. 509-512
We tested the hypothesis that the dark-adapted sensitivity of the near
central retina is lower than that of peripheral retina in 10-week-old
infants. A spatial two alternative forced-choice psychophysical metho
d was used to estimate the threshold for 2-deg spots presented 10 deg
and 30 deg from the center of a screen. Each 10-week-old infant (n = 1
1) and adult (n = 5) subject was tested at both eccentricities. Every
infant's threshold at 10 deg is higher than that at 30 deg. The median
difference between the infants' thresholds at 10 deg and 30 deg is ab
out 0.5 log unit. Whereas the scotopic thresholds of adults at 10 deg
and 30 deg are virtually identical, the thresholds of infants' near ce
ntral retina are higher than those in more peripheral retina. Delayed
maturation of the near central rod outer segments with consequent lowe
r quantum catch may be the primary determinant of this infantile sensi
tivity pattern.